I'm definitely biased as I grew up watching this series when it aired on TV. But I've recently started catching up with the latest episodes online, and I personally think the show just got even better throughout time.
The jokes and general style of humor gets random, the shots get even more ridiculous, and most importantly, you can tell the creators knows how ridiculous it is and is, like many kids' shows, not to be taken seriously. Of course they win (almost) all the time and perform the most unnecessary kicks and passes, but that's all what makes it a very entertaining watch.
The characters are quirky and I love the diversity, what was in the beginning rather full of stereotypes, but I appreciate that the show represents so many nationalities. There are even episodes showcasing various techniques/sports/etc. From different countries, which is also a great way for the audience to learn more about so many cultures around the world.
Animation keeps getting better, and I've even been impressed by some scenes and how smooth the animation is. The expressions and movements are dynamic, and with this level of constant improvement, the recycled shots (especially of the fans) are definitely excusable.
The soundtrack is one if my favorite aspects of the show. The theme song is an absolute hit: epic, catchy and iconic. The background music fits perfectly to the episode its accompanying and incorporates so many elements from different genres, though I'm especially a huge fan of the electric guitar that plays during their some of their games.
I literally cannot recommend this show enough for people who just want a show that does its job well in entertaining. I grew really attached to the characters and their ups and downs, and I can say the same about some of my friends who are also fans of the show.
Thank you, creators, for having this show be available to watch for everybody.